Installation of a CANAIR 4C28 24,000 BTU wall-mounted heat pump in Saint-Mathias-sur-Richelieu

A wall-mounted installation designed to combine high capacity, technical access, and four-season comfort

In Saint-Mathias-sur-Richelieu, we installed a CANAIR 4C28 wall-mounted heat pump in a space where the interior configuration required a particularly methodical approach. The unit had to provide sufficient capacity to effectively handle a large air volume while fitting near the ceiling in an architectural environment characterized by dark surfaces, exposed ducts, and suspended lighting.

The photograph taken during our work shows the indoor unit with its panels open. This step allows our technicians to carefully inspect the connections, sensor positioning, drainage, electrical connections, and component assembly before permanently closing the casing. This level of verification is essential for a HVAC installation, because a heat pump must not only work at startup: it must remain stable, quiet, and accessible for maintenance for many years.

The model shown on the indoor unit’s nameplate corresponds to the CANAIR 4C28SEH24H21 model, associated with a nominal cooling capacity of 24,000 BTU/h. This capacity is suitable for large open spaces, certain commercial premises, homes with high ceilings, or areas with a thermal load exceeding that of a conventional residential room.

Why a 24,000 BTU wall-mounted heat pump was appropriate here

Choosing the right capacity is one of the most important decisions in any wall-mounted heat pump project. An undersized unit will run almost continuously during peak periods. It may struggle to reach the requested temperature, especially during heat waves or very cold days. Conversely, an oversized unit may run excessively short cycles, which can compromise summer dehumidification, comfort, and the service life of certain components.

In this project in Saint-Mathias-sur-Richelieu, several visible characteristics justified a high-capacity unit:

• a large interior volume;
• an installation near a high ceiling;
• an area that appears largely open;
• dark ceiling materials that may absorb more heat;
• a need to project air over a good distance;
• a layout requiring high, evenly distributed airflow.

The 24,000 BTU CANAIR 4C28 series provides a nominal heating capacity of 29,000 BTU/h, with a modulating range reaching approximately 29,700 BTU/h. At an outdoor temperature of -15 °C, the advertised nominal heating capacity is 24,200 BTU/h, with an indicated coefficient of performance of 2.34. The documentation also indicates efficiency of up to 21.0 SEER2 and 13.5 HSPF2 IV for this configuration.

These figures never replace a heat-load calculation, but they help explain why this machine represents a serious solution for a demanding space.

A heat pump suited to the climate of Saint-Mathias-sur-Richelieu

In Saint-Mathias-sur-Richelieu, as elsewhere in Montérégie and on Montreal’s South Shore, a heat pump must cope with very different conditions throughout the year. The unit must efficiently remove humidity during the summer, maintain a stable temperature during transitional periods, and provide heating when the mercury drops well below freezing.

The CANAIR 4C28 is designed to provide heating down to an advertised outdoor temperature of -30 °C. Its cooling operating range also extends down to -30 °C, a relevant feature for certain commercial or technical applications requiring cooling even when it is cold outside.

The system uses Inverter technology, which adjusts the compressor frequency according to actual demand. Rather than operating only at full capacity and then shutting down, the heat pump can modulate its output. This modulation helps to:

• reduce abrupt temperature fluctuations;
• limit repeated start-ups;
• maintain more consistent operation;
• improve acoustic comfort;
• adapt energy consumption to the building’s needs.

This modulation capacity is particularly useful in a large space, where air temperature can vary between floor level and ceiling level.

An indoor unit designed to move a large volume of air

The 24,000 BTU version of the CANAIR 4C28 can provide indoor airflow of approximately 812 cu. ft./min. in Turbo mode. Its various fan speeds make it possible to adjust air distribution to the actual conditions of the space.

This represents a significant advantage in a space where the unit is installed high up. The conditioned air must be projected far enough to prevent it from remaining concentrated near the unit. In heating mode, adjusting the louvers becomes particularly important because warm air naturally rises.

The unit offers several functions designed to improve everyday comfort:

• Turbo mode to reach the selected temperature more quickly;
• Silent mode to limit noise when full power is not required;
• Follow Me function, which uses the remote control’s sensor to manage the temperature more effectively near the occupant;
• automatic restart after a power outage;
• self-cleaning function designed to dry the heat exchangers;
• optional Wi-Fi control;
• a function that limits the delivery of cold air at startup in heating mode.

The self-cleaning function does not, however, replace proper HVAC maintenance. The filters, blower wheel, evaporator, condensate pan, and drain must be inspected and cleaned according to the unit’s use and the building’s conditions.

Positioning near the ceiling required precision

The indoor unit was installed very high on the wall, immediately beside a corner and beneath an exposed ceiling structure. This type of configuration requires more than simple aesthetic alignment.

We must maintain the necessary clearances around the unit to allow for:

• proper air intake from above;
• opening of the front panel;
• removal and cleaning of the filters;
• access to the electrical connections;
• inspection of the drain pan;
• the possible removal of certain components;
• unobstructed airflow.

The photograph clearly illustrates why this access must be planned during installation. The casing is open and the internal components are accessible, despite the proximity of the ceiling and adjacent wall. A unit installed a few centimetres too high or too close to an obstruction can become unnecessarily difficult to service.

During several service calls performed by our teams in Montréal, Laval, Longueuil, the North Shore and the South Shore, we encounter units whose panel can no longer be fully opened. This mistake turns what would normally be a simple cleaning into a complex service call. At AirGreen, we therefore take future maintenance into account before securing the wall plate.

Checking the Connections Before Closing the Cabinet

The fully visible opening in the photo corresponds to an important stage of the work. Before closing the unit, we carry out a series of checks.

Electrical and Communication Connections

The CANAIR 4C28 uses a communication cable between the indoor and outdoor units. For the 24,000 BTU version, the documentation specifies a connection cable of type 14/4 AWG.

Each conductor must be connected to the proper terminal. A reversal or an insufficiently tightened connection can cause an error code, intermittent operation, or undesirable overheating.

Condensation Drainage

In air conditioning, the indoor evaporator produces condensation water. The drain must have a continuous slope when drainage occurs by gravity. Avoid:

• reverse slopes;
• crushed sections;
• improperly fitted connections;
• water pockets;
• an outdoor outlet placed too close to an opening;
• a discharge that could cause damage to the building.

We test the drainage before closing the unit. This step significantly reduces the risk of a leak appearing after several hours of air conditioning.

Refrigerant Piping

For the 24,000 BTU model, the specified diameters are 1/4 in. for the liquid line and 1/2 in. for the gas line. The stated maximum piping length is approximately 164 feet, with a maximum height difference of 82 feet.

In the field, the quality of flare fittings remains critical. The fittings must be prepared properly, tightened to the appropriate torque, and checked for leaks. A complete vacuum is then necessary to remove air and moisture from the circuit before releasing the refrigerant.

R-454B Refrigerant and Additional Precautions

This generation of CANAIR 4C28 uses R-454B refrigerant, classified as A2L. It has a lower global warming potential than some refrigerants used in older generations of heat pumps, but it is slightly flammable.

This characteristic requires compliance with work methods, clearance requirements, handling procedures, and the specific requirements for A2L equipment. The indoor unit includes a leak detection device. According to the manufacturer's documentation, the unit can display an error code and automatically stop operating when a refrigerant leak is detected.

The installation of an R-454B system must therefore not be improvised. It requires the appropriate tools, trained technicians, and a clear understanding of the unit's design.

A large indoor unit, intelligently integrated

The 24,000 BTU indoor unit measures approximately 46.85 in. wide, 11.20 in. deep, and 14.59 in. high. Its size is significantly larger than that of a small 9,000- or 12,000-BTU wall-mounted air conditioner.

In this project, the wall and the room's volume could accommodate this width without creating a disproportionate installation. The elevated location also helps free up usable space while allowing the air to circulate throughout the room.

However, choosing a high-capacity unit should never be based solely on the availability of a large wall. The capacity must match the heating and cooling needs, and the location must allow for good air circulation.

What this CANAIR 4C28 installation demonstrates about the quality of an HVAC project

The visible finish represents only part of the work

Once the cover is closed, the customer primarily sees a white unit mounted on the wall. However, the reliability of the installation depends mainly on the hidden elements:

• the strength of the mounting plate;
• the airtightness of the wall penetration;
• continuous insulation of the refrigerant lines;
• the tightening of the connections;
• the quality of the vacuum;
• the drain slope;
• compliance with electrical protections;
• the positioning of the wires and sensors;
• programming and final testing.

The photo taken during this installation in Saint-Mathias-sur-Richelieu illustrates this reality. Before the unit is closed up and ready to operate, every internal detail must be checked.

The costliest mistakes to avoid

When a homeowner compares quotes for a wall-mounted heat pump installation, the price of the unit should not be the only criterion. A less expensive installation can result in significant expenses if certain steps are overlooked.

Among the errors we regularly correct are:

1. a heat pump selected without a sufficient load assessment;
2. an indoor unit installed too close to the ceiling;
3. a drain without an adequate slope;
4. a poorly sealed wall opening;
5. insufficiently insulated pipes;
6. an outdoor unit installed too low for Quebec winters;
7. insufficient clearance for maintenance;
8. vibrations transmitted to the structure;
9. a vacuum procedure that is too short or not verified;
10. an electrical configuration incompatible with the manufacturer’s requirements.

For the 24,000 BTU model presented here, the outdoor unit requires, among other things, a minimum circuit ampacity of approximately 24.9 A and a listed maximum protection of 25 A. These values must be confirmed on the nameplate of the delivered equipment and incorporated into the electrical planning.

Commissioning adapted to the building

Commissioning is not limited to turning on the unit and checking whether hot or cold air comes out. We check operation in the various modes, louver movement, air temperatures, unusual noises, vibrations, drainage, and the remote control’s response.

We also explain to the client the practices that promote efficient operation:

• keep the temperature setting relatively stable;
• avoid constantly turning the unit off during periods of high demand;
• clean the filters regularly;
• do not obstruct the air return;
• clear the outdoor unit after snow accumulates;
• schedule a thorough maintenance service when the turbine or heat exchanger accumulates dirt.

A suitable solution for Saint-Mathias-sur-Richelieu and the greater Montreal region

This installation of a 24,000 BTU CANAIR 4C28 wall-mounted heat pump in Saint-Mathias-sur-Richelieu illustrates how we adapt each project to the architecture, air volume, technical access, and the client’s actual needs.

The unit offers high heating capacity, high airflow, Inverter technology, and advertised operation down to -30 °C. However, its performance depends directly on the quality of the installation.

At AirGreen, we carry out air conditioning, heating, and wall-mounted heat pump projects in Saint-Mathias-sur-Richelieu, Montreal, Laval, Longueuil, the North Shore, and the South Shore. Our approach involves choosing the right capacity, planning an accessible location, protecting the building against infiltration, and completing a full commissioning before considering the work finished.